Natural Semantics (2)

• Sequents : hyp |- p(S,...), p an assertion about S, the subject

• The type of a sequent is called a judgment

• Inference rules and axioms

  • mem |- X : v (provided X:v in mem)

  • env.X |- P
    -------------
    X |- declare X in P

• A formal system in which properties can be proved